let n=0.1+0.2;

test('小数误差-toBe',()=>{
    expect(n).toBe(0.3);
});


test('小数误差-toEqual',()=>{
    expect(n).toEqual(0.3);
});


test('小数误差-toBeCloseTo',()=>{
    expect(n).toBeCloseTo(0.3);
});